Ceramics, metals, and synthetic resins have been widely used for electrical home appliances, electronic parts, machine parts, automotive parts, and other uses, because they are excellent in durability, heat resistance, and mechanical strength. In some cases, these materials are adhered to or made into composite with an elastomeric material excellent in flexibility according to their uses, other constituting parts, and methods of use, for example, for fixing these materials to other structural members, absorbing shock, preventing damages, and sealing.
As such elastomeric material, a styrene-based thermoplastic elastomer excellent in flexibility, mechanical properties, and moldability can be suitably used. The styrene-based thermoplastic elastomer referred to herein is a block copolymer having a polymer block constituted by aromatic vinyl compound units and a polymer block constituted by conjugated diene units and a hydrogenated product of the block copolymer. However, since the adhesion strength of the styrene-based thermoplastic elastomer to ceramics and metals are poor because of its low polarity, the styrene-based thermoplastic elastomer cannot be fuse-bonded to these materials without an additional treatment. To eliminate this problem, several methods have been proposed, in which the surface of ceramics, metals, or synthetic resins is coated with an adhesive or treated with a primer before adhering the styrene-based thermoplastic elastomer to ceramics, metals, or synthetic resins (Patent Documents 1 to 6).
However, the methods disclosed in Patent Documents 1 to 6 include complicated steps and also the productivity is low to increase production costs.
To eliminate this problem, a thermoplastic polymer composition containing a styrene-based thermoplastic elastomer and a polyvinyl acetal, which is excellent in adhesion to ceramics, metals, and synthetic resins, is proposed (Patent Document 7). The proposed thermoplastic polymer composition adheres to ceramics, metals, and synthetic resins only by heat treatment without adhesive or treatment with a primer.